Slow light waveguide

This slow light waveguide includes an initial region which extends, along an optical axis, from a start starting from which the width of a central waveguide begins to continuously decrease up to an end beyond which the width of the central waveguide no longer decreases up to the end of a slowing section, this initial region overlapping a broadening region where the length of lateral teeth continuously increases, a final region which extends, along the optical axis, from a start starting from which the width of the central waveguide begins to continuously increase up to an end beyond which the width of the central waveguide no longer increases, this final region overlapping a narrowing region where the length of the lateral teeth continuously decreases.